Anatectic Granitic Pegmatites from the Eastern Alps: A Case of Variable Rare-Metal Enrichment During High-Grade Regional Metamorphism – I: Mineral Assemblages, Geochemical Characteristics, and Emplacement Ages

Konzett, Jürgen; Schneider, Tobias; Nedyalkova, Latina; Hauzenberger, Christoph; Melcher, Frank; Gerdes, Axel; Whitehouse, Martin J.

doi:10.3749/canmin.1800008

Cited by 29 publications

(30 citation statements)

References 62 publications

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“…According to [4,5], the rare-element pegmatites in the Kalu'an-Azubai pegmatite field are typical LCT-family pegmatites, which exhibit geochemical signature similar to that of S-type granites derived from partial melting of (meta)sedimentary sources [51]. There are basically two schools of thought regarding the petrogenesis of rare-element pegmatites: (1) fractional crystallization of granitic magmas [37,47,[51][52][53] and (2) direct anatexis [54][55][56][57][58]. The first model strongly relies on the granite-pegmatite relationship and the regional zonation of pegmatite groups that can reflect distinct differentiation of granitic magmas.…”

Section: Implications For the Formation Of The Kalu'an-azubai Rare-elmentioning

confidence: 99%

“…For example, the Separation Rapids Pegmatite Group exhibits a clear genetic link to the nearby fertile S-type granitic pluton (the Separation Rapids pluton) [42]. However, this model often faces challenges in cases where no parental granites can be linked to rare-element pegmatites [57,59,60]. Alternatively, an anatectic origin has been proposed by several authors [55,57,58] to explain the formation of rare-element pegmatites without parental granitic plutons.…”

Section: Implications For the Formation Of The Kalu'an-azubai Rare-elmentioning

confidence: 99%

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Columbite U-Pb Geochronology of Kalu’an Lithium Pegmatites in Northern Xinjiang, China: Implications for Genesis and Emplacement History of Rare-Element Pegmatites

et al. 2019

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The Kalu’an-Azubai pegmatite field, one of the most important rare-metal metallogenic regions in China, contains a large number of pegmatite dikes belonging to spodumene and lepidolite subtypes. Columbite-group minerals (CGMs) collected from three spodumene subtype pegmatites (No. 802, No. 803, and No. 805 pegmatites) were analyzed for major element contents using EPMA (electron probe micro-analyzer) and dated using LA-ICP-MS (laser ablation-inductively coupled plasma mass spectrometer). The crystallization ages of the CGMs from No. 802, No. 803, and No. 805 pegmatites are 209.5 ± 1.4 Ma (2σ), 198.3 ± 2.0 Ma (2σ), and 224.3 ± 2.9 Ma (2σ), respectively. Oscillatory zoning and/or sector zoning along with the associated mineral assemblages suggest that the dated columbite is of magmatic origin. The crystallization ages of the columbite grains thus represent the emplacement ages of the Li pegmatites. Therefore, our dating results indicate that there were three emplacement events of the Li-rich pegmatite-forming melts in a timeframe of ~30 Ma. In combination with previous studies, we conclude that the Li pegmatites were formed before the Be-Ta-Nb pegmatites (~194–192 Ma), which precludes the genesis of rare-metal pegmatites via fractional crystallization of a granitic magma in the Kalu’an-Azubai region.

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Section: Implications For the Formation Of The Kalu'an-azubai Rare-elmentioning

confidence: 99%

Section: Implications For the Formation Of The Kalu'an-azubai Rare-elmentioning

confidence: 99%

Columbite U-Pb Geochronology of Kalu’an Lithium Pegmatites in Northern Xinjiang, China: Implications for Genesis and Emplacement History of Rare-Element Pegmatites

et al. 2019

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“…However, pegmatites with a missing apparent parental granite are common [3], and it is suspected that the source granite occurs at depth [30]. On the other hand, studies published in the 2010s on the anatectic origin of granitic pegmatites in Europe and North America demonstrate that there are "thousands of pegmatites without parental granites" [13], i.e., pegmatite fields can be unrelated to a source granite and instead form by partial melting and anatexis of crustal material [4,13,14,[35][36][37][38][39], or energy and melt circulation along deep lithospheric fault zones [40]. In the current literature, there are numerous descriptions of pegmatite sub-classifications, but to date there is no universally accepted model explaining the diverse features and genesis of granitic pegmatites [39].…”

Section: Definition and Classificationmentioning

confidence: 99%

“…This model is currently challenged by a number of authors who outline evidence for an anatectic origin of pegmatite melts, e.g. [4,13,36,37,47]. Whilst pegmatite fields can be zoned, the zonation is in some cases not spatially related to a pluton, but to individual pods of pegmatitic melt.…”

Section: Formation Rare Metal Enrichment and Geodynamic Settingmentioning

confidence: 99%

“…Traditional model of regional zonation and rare metal enrichment of pegmatites and pegmatite fields related to S-type granite plutons implying that zoned pegmatite fields are related to and have a similar age as a nearby granite intrusion (modified from [26]). This model is currently challenged by a number of authors who outline evidence for an anatectic origin of pegmatite melts, e.g., [4,13,36,37,47]. Whilst pegmatite fields can be zoned, the zonation is in some cases not spatially related to a pluton, but to individual pods of pegmatitic melt.…”

Section: Formation Rare Metal Enrichment and Geodynamic Settingmentioning

confidence: 99%

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Tools and Workflows for Grassroots Li–Cs–Ta (LCT) Pegmatite Exploration

Steiner

2019

Minerals

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The increasing demand for green technology and battery metals necessitates a review of geological exploration techniques for Li–Cs–Ta (LCT) pegmatites, which is applicable to the work of mining companies. This paper reviews the main controls of LCT pegmatite genesis relevant to mineral exploration programs and presents a workflow of grassroots exploration techniques, supported by examples from central Europe and Africa. Geological exploration commonly begins with information gathering, desktop studies and Geographic Information System (GIS) data reviews. Following the identification of prospective regional areas, initial targets are verified in the field by geological mapping and geochemical sampling. Detailed mineralogical analysis and geochemical sampling of rock, soil and stream sediments represent the most important tools for providing vectors to LCT pegmatites, since the interpretation of mineralogical phases, deportment and liberation characteristics along with geochemical K/Rb, Nb/Ta and Zr/Hf metallogenic markers can detect highly evolved rocks enriched in incompatible elements of economic interest. The importance of JORC (Joint Ore Reserves Committee) 2012 guidelines with regards to obtaining geological, mineralogical and drilling data is discussed and contextualised, with the requirement of treating LCT pegmatites as industrial mineral deposits.

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Alpine eclogite-facies modification of Li-Cs-Ta pegmatite from the Wolfsberg lithium deposit, Austria

Keyser

Müller

Steiner³

et al. 2023

Miner Deposita

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The Wolfsberg lithium deposit in Austria is one of the largest Li-Cs-Ta pegmatite resources in Europe. The deposit is part of the Austroalpine Unit Pegmatite Province in the Eastern Alps that formed during the high-temperature, low-pressure Permian extensional event and was subsequently overprinted by Cretaceous eclogite-facies metamorphism during the Alpine orogeny. The two pegmatite types distinguished at the deposit, amphibolite hosted-(AHP) and mica schist hosted-(MHP) pegmatite, consist of quartz, albite, K-feldspar, muscovite and spodumene with accessory apatite, beryl and columbite. Both pegmatite types have similar peraluminous granitic compositions and element distribution patterns. However, the AHP contains higher Li and Cs concentrations. Both pegmatite types display LREE-enriched/HREE-depleted chondrite-normalized REY patterns that suggest derivation from partial melting of basement mica schist during the Permian HT/LP extensional event. The Alpine metamorphism more strongly affected the MHP relative to the AHP, resulting in recrystallization of primary assemblages by metamorphic assemblages with lower rare-metal concentrations, and development of a strong foliation, during which (re)mobilized elements (e.g., Li, Cs) were concentrated along localized shear zones. Recognition of element remobilization in MHP associated with metamorphic overprinting may bear important implications towards mineral exploration for Li-Cs-Ta pegmatite in other strongly metamorphosed terranes.

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Anatectic Granitic Pegmatites from the Eastern Alps: A Case of Variable Rare-Metal Enrichment During High-Grade Regional Metamorphism – I: Mineral Assemblages, Geochemical Characteristics, and Emplacement Ages

Cited by 29 publications

References 62 publications

Columbite U-Pb Geochronology of Kalu’an Lithium Pegmatites in Northern Xinjiang, China: Implications for Genesis and Emplacement History of Rare-Element Pegmatites

Columbite U-Pb Geochronology of Kalu’an Lithium Pegmatites in Northern Xinjiang, China: Implications for Genesis and Emplacement History of Rare-Element Pegmatites

Tools and Workflows for Grassroots Li–Cs–Ta (LCT) Pegmatite Exploration

Alpine eclogite-facies modification of Li-Cs-Ta pegmatite from the Wolfsberg lithium deposit, Austria

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